Communications satellites are commonly required to receive, process, and transmit signals across multiple communications channels. For this purpose, such satellites are typically provided with an output multiplexer (OMUX), an example of which will be briefly described with reference to FIG. 1.
The output multiplexer 100 is of a type commonly referred to as a manifold multiplexer, comprising a plurality of bandpass filters 101, 102, 103, 104 disposed at varying lengths along a manifold 105 having an input 107. Each filter 101, 102, 103, 104 attenuates any frequencies within an input signal a, b, c, d which fall outside of the filter's passband, a center frequency of which can be tuned by manually adjusting a tuning screw 106. The filtered signals a′, b′, c′, d′ are combined within the manifold into a frequency-multiplexed output signal a′+b′+c′+d′. However, each filter has a separate input. The output multiplexer does not function as a multi-band filter.